Thanks for the correction, Gilles! Could you give an example of how globbing can mess up the set -- without -f? I tried with a directory a[bar] on the same level as directories ab, aa and ar, but did not succeed. (EDIT: Succeed in failing, that is. I want to know how it goes wrong.)
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janmoesenNov 10 '11 at 7:43

Note that this listing can be a little misleading in the presence of symbolic links. For example, if /foo/bar is a symbolic link to /hello/world which is itself a symbolic link to /one/two, and all of /foo, /hello and /world are world-readable (say mode 755) but /hello is not readable to user Alice, then Alice won't be able to reach /foo/bar, yet the listing above will show only world-readable directories.